Apparatus for adjusting planetary thread rolling machines



April 12, 1955 J. w. BATCHELDER APPARATUS FOR ADJUSTING PLANETARY THREAD ROLLING MACHINES 2 Shets-Sheet 1 Filed Nov. 16, 1948 v INVENTOR James m Ba/che/der ATTO EY April 12, 1955 J. w. BATCHELDER 2,705,895

APPARATUS FOR ADJUSTING PLANETARY THREAD ROLLING MACHINES Filed Nov. 16, 1948 2 Sheets-Sheet 2 Surface speed of inner die l/ l'lcumferenlial speed of work piece axis 2/044} 7 RPM.

Circumferenfio/ speed of pw/rer l6 0 5/01/0007 outer die !NVEN TOR vbmes W. Bare/raider ATI'O United States Patent APPARATUS FOR ADJUSTING PLANETARY THREAD ROLLING MACHINES James W. Batchelder, Ascutney, Vt., assignor, by mesne assignments, to Batchelder Engineering Company, Springfield, Vt., a corporation of Vermont Application November 16, 1948, Serial No. 60,302

2 Claims. (Cl. 80-7) This invention relates to thread rolling, and particularly to the adjustment of thread rolling dies, preferably of the planetary type, to eliminate practically completely the need for rolling threads on successive trial work pieces. Planetary thread rolling die systems comprise a central cylindrical die and a segmental, internally threaded outer die surrounding it. The inner die is multiple threaded, having say 11 threads. The threads of the segments are preferably ground with the segments clamped to form portions of an (n+2)-threaded annulus and then shifted into thread rolling position as discussed in my copending application Ser. No. 60,301 filed November 16, 1948, now abandoned. Work blanks are introduced between the central die and each segment by pushers oscillating in arcuate paths. It is necessary that the dies be so aligned at the instant at which theygrip the work blank that the thread elements of the inner and outer dies which lie diametrically across the work piece are exactly 180 out of phase with each other.

The manner in which this coordination between the two dies and the pusher is accomplished in accordance with this invention will now be described with reference to the accompanying drawings, in which Fig. 1 is a fragmentary plan of the central die, three segments of the external die, and the pusher associated with one of the segments;

Fig. 2 is a diagrammatic view illustrating the first step in the alignment of the segment and the central die;

Fig. 3 is a similar view showing the alignment of the dies and the pusher;

Fig. 4 is a detail of a gauge used in the alignment procedure;

Fig. 5 is a detail of mechanism for operating the pushers;

Fig. 6 is a detail section of the mounting for the pusher operating cam; and

Fig. 7 is a cam motion chart showing the relation between the motion of the pusher and that of the dies.

As described in my copending application Ser. No. 792,296 filed December 17, 1947, now Patent No. 2,666,349, granted January 19, 1954, of which the present application is a continuation in part, a central cylindrical externally threaded die 1 is surrounded by a plurality (preferably three or more) segmental internally threaded dies 2 having an internal radius greater than that of the cylindrical central die by the pitch diameter of the screw to be rolled. The segmental dies are multiple threaded with a number of threads two greater than the number on the inner die. The increase in the number of threads in the outer dies preserves the same helical angle in spite of the increase in diameter.

Once a work piece is grasped between the dies at a time when the thread elements on the dies diametrically opposite are 180 out of phase, rotation of the inner die will roll the work piece along the outer segment and will itself roll over the work piece, and the same phase relationship will be preserved with of course progressively different thread elements. It is of great importance that the work piece should be introduced between the dies when the match points on the inner and outer dies are exactly 180 out of phase, and the present invention is directed to a method and an apparatus whereby the registration of the dies and the starting pusher can be accomplished with a minimum of setting-up time.

To this end each outer segment is held by clamps 3 to a die-holding block 4, which in turn is held to its seat on the machine frame by a screw 5. The die block 4 Patented Apr. 12, 1955 adjacent to each end is provided with a rear inclined face portion which bears against the forward inclined face of a pivot pin 6 which is mounted for vertical adjustment in order to shift the end of the die block towards or away from the central die. This adjustment is made by means of a screw 7 having a flange 8 engaging in a laterally opening slot in the forward inclined face of the screw. By adjusting the pivot pin 6 at one end the die block is rocked about the pivot pin at the other end. This permits either end portion of the stationary die segment to be adjusted toward and from the periphery of the central rotary die independently. No circumferential adjustment of the die segments is provided, the segments being positioned symmetrically about the central die by end abutments 40. When in adjusted position, the die block is clamped firmly in position by the clamp screw 5. This screw is threaded in an inclined position into the machine frame, so that it not only clamps the die block downwardly against the upper part of the frame but also forces the block outwardly against the inclined face of each of the pivot pins 6. The segments are adjusted as shown in exaggerated form in Fig. 1 so that they present a tapering throat 9 between themselves and the central die. Preferably, also, the end portion 10 of the segment is curved slightly outwardly, this starting radius being for the purpose of facilitating the placing of the work blank between the dies. Since, for reasons of ready replaceability and so that they can be inverted in the machine when worn, the segments are symmetrical about their midpoints, a similar starting radius 11 appears at the leave-01f end of the segment.

A pusher finger 12 is associated with each segmental die, and is mounted on a spider 13 at the top of a vertical shaft 14 preferably passing through the spindle carrying the inner die 1. Theinner die is driven by a hypoid gear meshing with a pinion 16 on a drive shaft 17. An extension of this drive shaft operates through a gear box 18 (more completely described in my copending application Ser. No. 792,296) to drive a camshaft 19 shouldered at 20 to receive a wedge collar 21 upon which the face cam 22 is mounted. The cam is held against a flange 23 on the shaft when the Wedge is tightened in place by a nut 24- and washer 25. By loosening the nut the cam may be freed for angular adjustment.

A cam roll 26 is mounted on one end of a rocker 27 pivoted at 28 and pressed on by a spring 29 so as to hold the roll against the cam. The second end of the rocker 27 is pivoted at 30 to a link 31 in turn pivoted at 32 to an arm 33 secured to the shaft 14 which carries the spider for the pushers. A cam 34 is pivoted to the frame at 35 and by means of a control rod 36 can be swung in a counterclockwise direction to engage the pivot 30 and hold the rocker in any position desired. In the adjustment of the dies the cam 34 is moved until it holds the rocker 27 in a position corresponding to that of the pusher at the matching position, as will now be further defined.

The pusher is given a motion which for a considerable period of travel has the same speed as the axis of the work piece as the latter is rolled between the dies. Since the outer dies are stationary during rolling while the inner die rotates continuously, the work piece is in the same relation as the pinion in a similar epicyclic gear train. The speed of translation of the axis of such a pinion is given by nV/2(n+1) where V is the linear speed of the inner die, taken of course on the pitch diameter. The relationship is shown to scale in Fig. 7. The speed of the work axis is not exactly one half the speed of the inner die, but is not far from it. The match point of the pusher is taken somewhere near the middle of the motion of the pusher when traveling at the speed of the work axis, so that the blank will be traveling at the correct speed at the time it is brought into engagement with the dies.

To get the dies into proper registering position they are coupled together by a gauge pin 37 shown in Fig. 4 on an enlarged scale. The pin is preferably hardened, and threads 38 accurately ground in it of the same pitch and tooth form as the dies. The outer portions 39 of the threads are not, however, present, they being removed to a diameter equal to that of the unthreaded work blank. If the gauge pin is introduced between the dies in any convenient position (Fig. 2) and the inner die oscillated back and forth while pushing the loosened die block 4 towards the central die, the gauge pin will engage the threads and the proper phase relation of the threads readily determined by feel. Once the threads on both dies have meshed with those on the gauge pin, registry will be preserved no matter how the inner die is turned, since the only action is rolling the gauge pin along the threads of the outer die.

After setting the die segment in the desired position radially of the inner die the pusher 12 is brought up to the desired place by the cam 34 and the inner die rotated to bring the gauge pin just into contact with the pusher. The pusher operating cam 26 is thereupon rotated to make contact with the cam roll and clamped in place, and the cam 34 returned to its inactive position. The pusher is now timed with respect to the inner die so that it will deliver a blank firmly between the dies at exactly the time that the match points on the inner and outer dies are in alignment.

What I claim is:

1. A planetary thread rolling machine having an n-threaded central die and an outer segmented die the segments of which form parts of an internally (n+2)- threaded annulus, means for rotating the inner die, a pusher mounted for oscillation between the inner die and each segment, means releasably coupled to the inner die rotating means for oscillating the pusher at a speed during a portion of its path equal to the speed of the axis of a work blank being rolled, means for releasably mounting each die segment for rocking and radial movement with respect to the inner die, and a screw gauge threaded with the same pitch as the inner die but having the outer parts of its threads cut away to the diameter of an unthreaded work blank, said gauge being receivable between the inner and outer dies to couple them together in matching relation and being rollable along an outer die segment by rotation of the inner die to locate a predetermined point in the travel of the pusher at a matching point of the inner and outer dies.

2. A thread rolling machine having dies engaging opposite sides of a work blank, means for causing relative rotating movement between the dies, a pusher mounted for oscillating movement between the dies, means timed with the die moving means to move said pusher in a path at a speed during a substantial portion of which is equal to the translational speed of theaxis of a work blank being rolled, and a gauge having thread elements of the same pitch as the dies but having the outer parts of the thread elements cut away to the outside size of an unthreaded work blank to provide a pusher gauging surface,

said gauge being receivable between the dies to couple.

them together in matching relation and being shiftable by relative movement of the dies to locate a predetermined point in the travel of a pusher at a matching point of the dies.

References Cited in the file of this patent UNITED STATES PATENTS 

